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University of Wyoming

University of Wyoming Physics & Astronomy Colloquium Series

Fridays -- 4:10 PM -- Prowse Room 234

Pre-Colloquium tea served at 3:45 in the Cinnamon Room, PS 237

Spring 2007 Schedule

Jan 26 Michael Spee (Lockheed Martin)
Careers in Aerospace Science at Lockheed Martin

As a graduate of the University of Wyoming and current Lockheed Martin employee I will be presenting an overview of my career. The presentation will step through good and bad choices I made during college as well as on my way to Lockheed Martin. There will be a brief company history as well as a description of some new and continuing projects at Lockheed Martin. I will discuss possible opportunities available to graduates with and without a masters degree and also summer internships.

Feb 9 Jeff French (U. Wyoming)
Energy Exchange Between the Atmosphere and the Surface in Hurricanes

Numerical and theoretical models of tropical cyclones (TCs) suggest that the maximum intensity of these storms is modulated by the ratio of energy supplied to the storms through heat from the ocean and energy removed through drag on the surface. Surprisingly, some recent investigations have suggested that atmospheric thermodynamic instabilities play no role in the intensification and maintenance of TCs. Thus, recent work has focused on gaining a better understanding of the magnitude of energy exchange between the atmosphere and the ocean (air-sea fluxes). Models used to forecast movement and intensity changes are highly sensitive to parameterizations of these fluxes, yet little is known about the magnitude of these fluxes in high wind environments.

In this colloquia, discussion will focus on the importance of air-sea fluxes to the intensification and maintenance of TCs and major factors that contribute to the modulation of these fluxes. Results from recent work that include estimates of air-sea fluxes in hurricanes taken from laboratory estimates and indirect measurements in storms will be presented. The first-ever direct measurements of air-sea fluxes in TCs in winds up to hurricane strength will also be presented.

Mar 5 Eric Heller (Harvard)
Picture Perfect: Persuasion, Politics, and Prejudice surrounding the scientific image, 1800-2006

How does the scientific image convince and convey? What is the role of the image in enhancing science, public understanding and funding of science, scientific theories, and scientists' careers? Why have some scientists looked down on the images, almost as if they were craven?  These issues are illustrated through the colorful history of wave physics, including some of the author's own work and images, including recent works of art.
Phi Beta Kappa Series Speaker
Time: 4:00
Place: Ag Auditorium

Mar 23 Rajib Ganguly (Wyoming)
Spewing Black Holes: Outflows from Active Galaxies

It has long been held that a disk accreting onto a supermassive black hole is the driver behind the incredible energy emitted by nuclei of active galaxies (AGN). Over the last decade, we have arrived at a paradigm describing an outflow that is driven off this disk that seems to explain several observables, from the broad single-peaked emission lines, to broad absorption lines. Understanding the physics of this outflow now seems to be a crucial component, not only in understanding the accretion process itself, but also in appreciating the affect of the AGN on the host galaxy and the surrounding intergalactic medium. In this talk, I will go over the basics of AGN outflows, work by the UW AGN group to understand the most extreme outflows, and efforts to unravel the overall demographics of outflows of all forms.

Apr 6 Richard Wade (Penn State)
The Origins of Hot Subdwarf Stars: Many Questions, Few Answers

The hot subdwarf stars (sdB stars, Extended Horizontal Branch stars) are core Helium-burning stars with very low mass Hydrogen envelopes. They are found in old, metal-poor globular clusters, somewhat younger metal-rich open clusters, and in the general field. In the globular clusters, these stars co-exist with red HB stars, which are expected to have similar masses, ages, and compositions but have much thicker H envelopes. How are the envelopes lost from the hot subdwarfs? Variable mass loss from single stars is an explanation with little predictive value. If mass loss is assisted by a close stellar companion, how can we show this? I will discuss several ways in which binary origin scenarios can be confronted with observations of field sdB stars. The observational picture is confused and limited in various ways. Is the search for a single origin for hot subdwarf stars destined for extinction, like the Triceratops?

Apr 13 Ted von Hippel (Southwest Research Institute)
White Dwarf Debris Disks and the Fate of Planetary Systems

I will present Spitzer and ground-based observations of five metal-polluted white dwarfs with circumstellar debris disks. Four of these objects are newly discovered. For two of the white dwarfs, I will present Spitzer 5.5-14 micron spectroscopy, highlighting the 9-11 micron emission feature caused by mixture of amorphous olivine and forsterite. The emitting region is located 0.1-5 Rsun from the WDs. Our measurements support the idea that disruptions of comets or asteroids created the debris disks. Based on the properties of these five stars, I interpret the bulk of the metal-polluted white dwarfs as resulting from planetary system bodies being ground down during the late stages of stellar evolution. If correct, this implies that >= 25% of all stars are orbited by terrestrial-type planets, asteroids, or comets.

Previous colloquia series: Fall 2002 Spring 2003 Fall 2003 Spring 2004 Fall 2004 Spring 2005 Fall 2005 Spring 2006 Fall 2006
Contact for program information: Daniel Dale (ddale @